Blender has stopped working: Crash on startup
For these kind of problems you should report a bug in the tracker, as there is really no 'useful answer' possible for this.

If every version of blender has simply 'stopped working' it is likely a problem with your computer (eg. drivers problem).
Otherwise you can try a daily build to see if the problem persists: 
buildbot
If it is a bug, report it: report a bug
If you need assistance try any of the listed options: http://www.blender.org/support/